1. Field of the Invention
This invention concerns a management method for conditional access data processing by at least two decoders, particularly in the field of access to Pay-TV events. It also concerns a decoder for carrying out this process.
2. Description of the Related Art
Generally, to be able to access an encrypted content corresponding to events broadcasted by Pay-TV operators, such as films, sports events or the like, it is necessary to purchase a subscription, a decoder and a security module. Some subscribers wish to have several decoders and several security modules so that several users can access broadcasted events from several televisions placed in different parts of their home.
In this case, the price asked for supplementary subscriptions, decoders and/or security modules is generally lower than the price asked for the first subscription, decoder and/or security module. However, the aim is to avoid a subscriber purchasing several decoder/security module units, by taking advantage of the price reduction for supplementary units and that he enables a non-subscriber third party taking advantage of this reduction or that he re-sells these units at a lower price than the normal purchase price.
A solution to avoid this situation consists in the imposition of operating conditions so that a decoder that has been removed from its environment no longer allows the decryption of encrypted content, while the same decoder operates in a conventional way as long as it remains in its environment. Thus, a decoder that has been resold or given to a third part cannot function.
A system allowing part of this aim to be achieved is described in the European patent published under the number EP 0 826 288. This patent describes a Pay-TV system in which a subscriber has at least two decoders, each decoder being associated to a smart card intended to allow the decryption of the content sent to the decoders connected to the television system. Each smart card contains a certain amount of data that allow its identification. This information, called “chaining data”, is for example a signature, a key or another determination element. All the cards connected to the same subscriber have at least one chaining data in common. The cards of different subscribers do not have any data in common.
The subscriber's smart cards, or at least one of them, are deactivated after a certain duration of use. The content sent to the decoder in question can no longer be decrypted. A deactivated card can be reactivated if the subscriber has another card that is still active and has a decoder connected to the same subscriber. To implement this, the system according to this invention operates in the following way. The data connected to an active card is first stored in the decoder into which this card is introduced. When a card is deactivated, it must be introduced into a decoder associated to an active card of the subscriber. The chaining data such as the signature, the key, etc., stored in the decoder, are authenticated with the deactivated card chaining data. If this data matches, the card is reactivated for a certain time duration. If the chaining data does not match, the card is not reactivated.
In this system, any decoder connected to an active card of the subscriber can allow the reactivation of a deactivated card of the same subscriber. In this way, if the subscriber's cards have been sold to people geographically close to the original subscriber, the people with a deactivated card can introduce this card into any decoder connected to an active card of the subscriber in order to re-start functioning. The deterrent effect aimed for in this invention is thus only partially achieved. Furthermore, reactivation must be carried out regularly and requires manipulation on the part of the user. These constraints are generally little appreciated by “honest” users. Moreover, there is a significant risk of wrong operation or of card loss.
Moreover, there is another simple way to avoid the constraints related to the process of this patent. In fact, it is sufficient for the buyer of an unauthorized decoder/smart card unit to purchase two units. Thus, a card can always be reactivated when it has been deactivated.